Manufacturers ship certain types of systems for controlling devices in an xe2x80x9cunprogrammedxe2x80x9d or xe2x80x9cuncommissionedxe2x80x9d state. That is, until the control system has been commissioned or programmed after installation, it will not function to properly control the device it is intended to control. The main reason for this is that many classes of controlled devices have such a large number of unique configurations or requirements that it is not possible to provide a preprogrammed control system for each possible configuration.
To deal with this situation, various methods for programming or commissioning such control systems during installation have been developed. Where the control system is electromechanical, programming can be as simple as positioning cams or stops appropriately. A very simple example of such a system is any of the light/appliance timers available at hardware stores. The user positions or activates cams or levers on a dial face of the timer to select the on and off times. Although very simple, this example is typical of many types of controller programming.
Where the control system is electronic, one needs a different approach. It is easy to provide these systems with one or more control switches for reset, startup, error or status readout, etc. and one or more indicator lights that signal mode, status, error, etc. These switches can be used for commissioning or programming these systems. U.S. Pat. No. 6,175,207 teaches one type of controller using an already present reset switch to select one of a number of preprogrammed operating modes as the one for the particular installation. Other systems have dedicated switches for programming input. It is possible to provide a standard keypad such as on a calculator, but this occupies scarce space, adds cost and tempts users to alter settings that an installer had previously recorded.
It is important in some applications to prevent reprogramming of control systems after initial programming. One of these situations (and the one concerning the inventors) involves the use of a mechanical actuator as the control device for opening, modulating, and (most importantly) closing a fuel valve of a burner. The mechanical actuator is controlled by an electronic controller that receives sensor data and commands from higher-level controllers or even users. A typical actuator can operate the fuel valve between closed and maximum openings with a smaller modulation range between closed and maximum which is active during the Run phase of the burner. Once the fuel control system has been professionally installed and configured, it is important that the user does not alter these installed settings for the fuel valve actuator. However, experience shows that one cannot rely on users to follow this rule. It is possible that user tampering with these settings can inadvertently create an unsafe or inefficient operating mode for the fuel control system.
User tampering is a serious concern for manufacturers of safety-related equipment of all types. On the one hand, users and manufacturers alike strongly desire that equipment shipped in an uncommissioned state be easily commissioned during installation. On the other hand, it is very important that tampering by unqualified persons with installed system settings be made as difficult as possible. Thus, conventional input devices like keypads and other easily accessible switches are undesirable because they make tampering too easy. In our system we reduce the temptation to tamper by making access to the setting controls difficult. It is also possible to require special key codes to put the control system in its commissioning mode, but for this particular application we prefer to control access to the commissioning switches.
It is also helpful in understanding the invention, to know the basics of electromechanical actuator design. An actuator typically has a small, relatively high-speed reversible motor driving a rotating output shaft or hub of some kind through a high-ratio reduction gear train. Typically though not always, the output shaft rotates through a fraction of a revolution over a period of several tens of seconds. Maximum rotation in each direction is limited by mechanical stops. The motor drives the gear train through a magnetic slip clutch that allows the motor to rotate without harm if the output shaft is locked for any reason. Actuators are for the most part of two types, foot-mounted and direct coupled. Foot-mounted actuators are bolted to a frame of some type, and have a shaft that connects to the controlled device""s input. Direct-coupled actuators have a rotating hub with a connection feature of some type such as a square or splined hole. The controlled device""s shaft clamps to the actuator hub, and then the actuator housing is bolted at a single point to the controlled device itself. These two attachments cooperate to hold the actuator in its operating position.
Where modulation of the actuator position is required, it is usually necessary to sense the angular position of the actuator output. This can be done in a variety of ways. One common system uses a variable rheostat connected to the actuator output shaft. The rheostat provides a current signal varying from 4-20 ma. nominal as the shaft rotates from one mechanical stop to the other. This varying current can be converted to a quite accurate digital indication of the shaft position. The controller uses the position signal to determine the shaft position and to provide the appropriate control signal. Actuators often have manual controls that allow a human to set a desired position, overriding any controller setting of the actuator position.
We have developed a system that permits easy commissioning of electrically or electronically controlled devices having status or position sensors and manual override of normal position control. Mechanical actuators having shaft position sensors and permitting manual positioning fall in this category. For purposes of commissioning, such a controlled device can be considered a manual input data source, by virtue of the position sensor output and the manual control. Then the system can be considered a data entry system for accepting manually generated data values.
In its broadest form, such a system comprises first and second data entry elements respectively providing first and second data entry signals responsive to a manual input applied to the respective data entry element. The first data entry signal typically encodes a single binary digit provided by a momentary contact switch, although this need not be. The second data entry element provides a signal encoding a plurality of data values such as those provided by a position sensor for a manually positionable device.
The system also includes a phase index memory element providing a phase signal sequentially encoding at least first and second distinct phase index values. The phase index memory element sequences the phase index values in the phase signal from the first and following phase index values to the next in order responsive to each first data entry signal. Most conveniently, a phase index can be a sequence of integers, say from one to five or any other desirable range.
An indicator element also forms a part of the system. The indicator element receives the phase signal and providing a different, humanly discernable indicator pattern for each phase index value. Finally, the system in its broadest form also includes a data recorder receiving the first and second data entry signals and the phase signal. The data recorder has at least first and second memory locations each for storing one data value. Each memory location is associated with one of the phase index values. The data recorder records the data value encoded in the second data entry signal in the memory location associated with the current value of the phase index and responsive to an occurrence of the first data entry signal.
One of the most useful embodiments uses as the second data entry element, a control element having an output element having a plurality of positions and a position sensor providing a position signal encoding the output element position. The manual input comprises an element or feature of the control element for manually positioning the output element. The preferred embodiment of the control element comprises a mechanical actuator having an output shaft forming the output element and changing position responsive to positioning power. A shaft position sensor comprises the position sensor. A manually operated switching element provides positioning power to change output shaft position responsive to operation of the switching element. Thus the element controlled by the controller also serves as its second data entry element. The installer can see or measure the shaft position, and can manually rotate the shaft to the position required.